Display screen or portion thereof for a graphical user interface



FIG. 1 is a front view of a display screen or portion thereof for a graphical user interface showing my new design; and,

FIG. 2 is a front view of a second embodiment which illustrates an example environment.

The long and short dashed broken line showing of a mobile terminal in FIG. 1 forms no part of the claimed design. The mobile terminal, display screen, and the text/words, numbers, symbols and images of the graphical user interface shown in broken lines in FIGS. 1 and 2 form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof for a graphical user interface, as shown and described. 